Composition and method for treating surfaces



United States Patent 3,397,150 COMPOSITION AND METHOD FOR TREATING SURFACES James Gordon Burt, Nottingham Township, Chester County, Pa., and Howard Elliot Phillips, New Castle, Del., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Mar. 15, 1%6, Ser. No. 534,427 15 Claims. (Cl. 252194) ABSTRACT OF THE DISCLOSURE Water is removed from solid surfaces by treating with a composition containing trichlorotrifluoroethane and a solute derived from a monoalkyl or dialkyl phosphate ester in which the alkyl groups each contain 6-20 carbon atoms, and a saturated aliphatic amino containing 1-3 alkyl groups attached to the amine nitrogen and a total of 6-20 carbons. These compositions prevent rusting of ferrous metal surfaces.

This invention relates to compositions for treating surfaces and more particularly to compositions containing a trichlorotrifluoroethane solution of certain phosphate esters neutralized with amines and to the method of treating surfaces therewith.

In many machining and cleaning operations, metal parts are brought into contact with water, with the result that the finished metal surface remains Wet. As is well known, water leads to more rapid corrosion of these metal surfaces. Many machined metal parts, such as bearings and precision valve components, cannot tolerate corrosion because of the fine tolerances usually required. In addition, certain metal parts, and particularly precision metal parts, must be completely dry before they are assembled. Ball, needle and roller bearings for example, if inserted in a race while wet, will corrode and freeze the bearing assembly. Accordingly, it is necessary that many metal parts be completely dried immediately after the machining or cleaning operation, and before they are assembled. A similar need exists for drying plastic and glass surfaces, particularly when these parts are to be used in combination with metal parts.

Heretofore, such parts have been dried by simple heating, but this is often undesirable since heating in the presence of water may cause corrosion. Moreover, heating requires handling which is also undesirable. Water has also been removed by treating with certain solvents such as acetone or alcohol. However, such liquids are toxic and flammable, and thus present operational hazards. Accordingly, a need exists for a method of removing water from surfaces .without heating in the presence of water or using flammable or toxic solvents.

As is well known, ferrous metal surfaces will rust, particularly if the surface is free of protective materials. Degreased metals are particularly prone to rusting since the surface is completely free of materials which would otherwise prevent contact of the surface with oxygen.

Rusting of many surfaces, while undesirable, is not particularly serious, providing the rust is removed before further treating such as painting, plating or the like.

3,397,150 Patented Aug. 13, 1968 'ice However, the slightest amount of rusting of the surface of precision ferrous metal parts, for example, ball bearings and the like, is a serious matter since such parts are machined and finished to very fine tolerances. Many methods have been developed for treating ferrous metal surfaces to prevent rusting. Because none of these methods are effective in all cases, there is a continuing need for improved methods of rust prevention.

It is an object of this invention to provide novel compositions which are useful for treating surfaces. Another object is to provide a method of removing water from metal and other surfaces without heating in the presence of water or using flammable or toxic solvents. Still another object is to provide an improved method of preventing rusting of ferrous metal surfaces without otherwise affecting the surface. These and other objects will become apparent from the following description of this invention.

Certain novel compositions have now been discovered which have outstanding utility for removal of water from solid surfaces and prevention of rusting of ferrous metal surfaces treated therewith. These compositions comprise 1,1,2-trichloro-1,2,2-trifluoroethane containing, dissolved therein, about 0.01 to 10% by weight of a solute derived from (a) alkyl phosphate ester selected from the group consisting of monoalkyl and dialkyl phosphate esters and mixtures thereof, in which the alkyl groups contain 6 to 20 carbons, and

(b) saturated aliphatic amine containing 1 to 3 alkyl groups attached to the amine nitrogen and a total of 6 to 20 carbons, said amine being present in an amount suflicient to substantially neutralize the phosphate ester.

Such compositions can be used to completely remove water from metal and other solid surfaces without heating in the presence of water or using flammable or toxic solvents. These compositions can also be used to prevent rusting of ferrous metal surfaces without any adverse effect on the surface.

The phosphate monoesters which are useful in the compositions of this invention are those having the structure n ROP (OH):

wherein R is an alkyl group containing from 6 to 20 carbons. The exact nature of the alkyl group is not critical so long as it contains the specified number of carbons. It may be straight chained such as hexyl, octyl, decyl, dodecyl, tridecyl, tetradecyl, hexadecyl or octadecyl, or branched chained such as isooctyl, Z-ethylhexyl, isodecyl, tertdodecyl, or the branched chain alcohols formed in the oxo process and known in the art as oxo alcohols. The dialkyl phosphates which may be used in accordance with this invention are those having the structure (ROhi OH wherein R is the same alkyl group as indicated above.

The saturated alipha ic amines which are used in accordance with this invention are those having the structure RN(R") wherein R is an alkyl group and each R"' is hydrogen or an alkyl group. R and the two R" groups together must contain a total of from six to twenty carbons. Thus, the amine may be a primary amine such as hexylamine, octylamine, 2-ethylhexylamine, l,l,3,3-tetramethylbutylamine, decylamine, dodecylamine, tetr-adecylamine, hexadecylamine, or octadecylamine; a secondary amine such as ethylbutylamine, dipropylamine, hexylmet hylamine, dibutylamine, decylmethylamine, butyloctylamine, dodecylmethylamine, tetradecylmethylamine, dioctylamine or octadecylmethylamine; or a tertiary amine such as triethylamine, decyldimethylamine, tr'ibutylamine, diethyloctylamine, tctradecyldimethylamine, hexadecyldimethylamine, decyldibutylamine, or octadecyldimethylamine. Mixtures of amines as are often available commercially, may also be used.

The compositions of this invention comprise 1,1,2-trichloro-l,2,2-trifiuoroethane and about 0.01 to by weight, based on the l,1,2-trichloro-1,2,2-trifiuoroethane, of a solute derived from alkyl phosphate ester and saturated aliphatic amine. Preferably the amount of solute is about 0.05 to 3%. The amount of amine present should be at least sufficient to substantially neutralize the phosphate ester and should not exceed about a 10% excess over the amount necessary to completely neutralize the phosphate ester. In general about one mole of amine per mole of phosphate ester is required to neutralize the phosphate ester since the second hydrogen in the monoalkyl phosphate is not reactive with the amine. Neutralization of substantially all of the reactive hydrogens in the phosphate ester is import since residues of unneutralized phosphate ester are difficult to remove from the surface. In some cases these acid residues may lead to corrosion of the surface.

These compositions are prepared by first mixing the phosphate ester with the required amount of amine, usually in the presence of sufficient solvent to maintain the mixture fluid during the preparation. The solvent is then removed and the desired amount of phosphate salt is dissolved in the trichlorotrifiuoroethane solvent.

The preferred compositions of this invention are those in which the solute is derived from a mixture of mono (tridecyl) and bis(tridecyl) phosphates neutralized with Z-ethylhexylamine, a mixture of monooctyl and dioctyl phosphates, in which the octyl group is derived from oxooctyl alcohol, neutralized with 2-ethylhexylamine or a mixture of monoand di-n-octyl and monoand di-ndecyl phosphates neutralized with Z-ethylhexylamine. Suitable surfaces from which water can be removed in accordance with this invention are not limited to any particular material but may be composed of any dimensionally stable, non-absorbent, insoluble, solid substance which may be used to manufacture shaped articles. Typical examples of suitable metals include ferrous metals, nickel and its alloys, chromium and its alloys, stainless steels, copper, brass, bronze, silver, aluminum, zinc, cadmium, magnesium and the like. Naturally, highly reactive metals such as the alkali metals are not contemplated. Other surfaces which may be treated for water removal include glass and plastics such as nylon, polyethylene. polycarbonate, and the like. The Water to be removed from the surface may be in the form of a thin film, droplets of various sizes or adsorbed water held by capillary attraction. The water may be substantially pure or it may be a dilute solution of a salt, detergent or soap. Such solutes should not be present in sufficient amount to make the water a solvent for the trichlorotrifiuoroethane composition.

Water removal is carried out by treating the surface with the trichlorotrifiuoroethane composition of this invention, whereby the trichlorotrifiuoroethane composition displaces the water. This can be accomplished by contacting the surface with the composition by spraying, brushing or otherwise applying the composition to or passing the composition over the surface, or by immersing the article in the composition.

Water removal is preferably carried out at ambient temperatures although lower or higher temperatures up to the boiling point of the composition may be used if desired. In sealed systems, temperatures above the normal boiling point of the composition may be used, although no special advantage is gained thereby. The time of treatment is not critical since a substantial amount of water removal is accomplished upon contact of the surface with the composition. As a practical matter, the surface will generally be in contact with the composition for about one minute although longer or shorter times can be used.

The treated surface may then be rinsed with trichlorotrifiuoroethane to remove traces of the solute. This step may be omitted if such traces are not harmful. Finally, the solvent is allowed to evaporate from the surface, leaving the metal surface completely clean and dry.

The compositions of this invention are also useful for the prevention of rust on ferrous metal surfaces. The preferred compositions for this use are those containing 1 to 3% of solute. The rust prevention treatment can be accomplished by contacting the surface with the composition by spraying, brushing or otherwise applying the composition to or passing the composition over the surface, or by immersing the article in the composition. Ambient temperatures are preferred, although the rust prevention process can be run at the boiling point of the composition, at higher temperatures, for example at C. under pressure, or at temperatures below room temperature.

After evaporation of the trichlorotrifiuoroethane solvent, the treated metal surface is left with a phosphate salt film which acts as a rust preventative. This film may also serve as an undercoating for paint as in phosphatizmg.

Although the reason is not understood, it has been found that l,l,2-trichloro-l,2,2-trifluoroethane is a useful solvent for the rust inhibiting compositions of this invention, while other solvents containing the same solutes are far less effective. For example, compositions containing water, alcohols, hydrocarbons or chlorinated hydrocarbons substituted for the trichlorotrifiuoroethane of the compositions of this invention do not have the superior rust inhibiting properties exhibited by the compositions of this invention.

The following examples, illustrating the novel compositions and methods of this invention, are given without any intention that the invention be limited thereto. All parts and percentages are by weight.

EXAMPLE 1 A total of 43 stainless steel miniature precision bearings of assorted sizes and with a gross weight of 74 grams, were rinsed in anhydrous methanol, and then air dried. These bearings were immersed in water and then shaken sharply in a Buchner funnel to remove all but the water that was held in many fine interstices by surface tension and capillary effect. The wet bearings were then treated for one minute with l,l,2-trichloro-1,2,2-trifluoroethane solutions as shown in Table I below, replaced in a dry Buchner funnel and flushed with a known quantity of anhydrous methanol. The methanol was collected and analyzed for water by the Karl Fischer method. By comparing the amount of water retained with the average amount retained by the same bearings without treatment (blank), the percent water removal was calculated.

The results obtained are listed in the table below. Solute A consisted of a mixture of mono(tridecyl) and bis(tridecyl) phosphates neutralized with 2-ethylhexylamine. Solute B consisted of a mixture of monoand di-oxo-ioctyl phosphates, where oxo-octyl designates phosphates derived from octyl alcohol prepared by the 0x0 process, neutralized with Z-ethylhexylamine. Solute C consisted of a mixture of monoand di-n-octyl and monoand di-n-decyl phosphates neutralized with 2-ethylhexylamine. All treatments were at room temperature except where otherwise stated in the table.

TABLE I Percent Percent Water Solute Solute in Treatment Removed Solution Compared to Blank Immersed with ultrasonic agita- 0 ion. Immersed at boil 14 0. Immersed with ultrasonic agita- 93 tion. 0. 05 Immersed at boil 81 0. 05 Immersed with hand agitatio 91 0. 05 Pumped stream of solution 99 0. 1 Dipped with hard agitation 89 1. 0 do 98 3 Pumped stream of solution 97 0.05 Immersed with ultrasonic agita- 96 tion.

EXAMPLE 2 An assortment of brass fittings weighing 90 grams were carried through the procedure of Example 1. All treatments were at room temperature. The results obtained are shown in Table II.

EXAMPLES Steel coupons 3 x 6 x 2 inch (76 x 152 x 0.8 mm.) were immersed at room temperature for one minute in a pickling bath composed of concentrated hydrochloric acid diluted with an equal volume of water. The surfaces were wiped clean, rinsed free of acid with tap and distilled water, then dried with acetone and finally 1,1,2-trich1oro- 1,2,2-trifiuoroethane. The coupons were then immersed to half their length in a 3% solution of an equal Weight mixture of mono(tridecyl) and bis(tridecyl) phosphates neutralized with Z-ethylhexylamine in 1,1,2-trichloro-1,2, 2-trifluoroethane for one minute. These coupons were then subjected to 100% relative humidity provided by live steam which resulted in water condensation on the surface. After six hours under such conditions, the untreated sections of the coupons were completely rusted while the treated sections were unaffected.

EXAMPLE 4 Steel coupons were treated as in Example 3 except that the 1,1,2-trichloro-1,2,2-trifiuoroethane solution contained 3% of a solution of the above additives in 20% kerosene. The untreated sections of the coupons were completely rusted while the treated sections were unaffected.

EXAMPLE 5 Coupons were treated as in Example 3 except that the 1,1,2-trichloro-1,2,2-trifluoroethane solution contained 3 of mixed mono-oxo-octyl and di-oxo-octyl phosphates neutralized with Primene-SIR, a commercial mixture of tertiary alkyl primary amines of the formula RNI-I in which R contains from 12 to 20 carbons. The untreated sections of the coupons were completely rusted while the treated sections were unaffected.

EXAMPLE 6 Coupons were treated as in Example 3 except that the 1,1,2-trichloro-1,2,2-trifluoroethane solutions contained 3% of monoand di-n-octyl and monoand di-n-decyl phosphates neutralized with Z-ethylhexylamine. The untreated sections of the coupons were completely rusted while the treated sections were unaffected.

6 EXAMPLE 7 Steel coupons, prepared and treated as in Example 3, were exposed to the atmosphere of an air conditioned room for 6 months. At the end of this period, the untreated sections showed a brownish haze of rust while the treated sections remained clear.

EXAMPLE 8 Steel coupons, pickled as in Example 3, were immersed for one minute at room temperature in 3% solutions of mixed mono(tridecyl) and bis(tridecyl) phosphates neutralized with 2-ethylhexylamine in each of the following solvents: 1,1,Z-trichloro-l,2,2-trifluoroethane, trichloroethylene, Stoddard solvent, methanol and water (dispersion). The treated coupons were exposed to steam as in Example 3 with the following results:

Condition of Solvent: coupon after 6 hours 1, l,2-trichloro-l,2,2-trifluoroethane No rust. Trichloroethylene Rust spotting. Stoddard solvent Heavy rust spotting. Methanol Minor rust spotting. Water Heavy rust spotting.

Although the invention has been described and exemplified by way of specific embodiments, it is to be understood that it includes all modifications and variations coming within the scope of the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

What is claimed is:

1. A trichlorotrifiuoroethane composition which comprises 1,1,2-trichloro1,2,2-trifiuoroethane as solvent and 0.01 to 10% by weight, based on the 1,1,2-trichloro-1,2,2- trifluoroethane, of a solute derived from the neutralization of (a) alkyl phosphate ester selected from the group consisting of monoalkyl and dialkyl phosphate esters and mixtures thereof in which the alkyl groups each contain 620 carbons, with (b) saturated unsubstituted aliphatic amine containing 1 to 3 alkyl groups attached to the amine nitrogen and a total of 6 to 20 carbons, said amine being present in an amount at least sufficient to substantially neutralize the phosphate ester and not exceeding a 10% excess over the amount necessary to completely neutralize the phosphate ester.

2. A composition of claim 1 containing 0.05 to 1% by weight of solute derived from (a) a mixture of monoand bis(tridecyl) phosphates, and (b) 2-ethylhexylamine.

3. A composition of claim 1 containing 0.05 to 1% 'by weight of solute derived from (a) a mixture of monoand di-oxo-octyl phosphates, and (b) Z-ethylhexylamine.

4. A composition of claim 1 containing 0.05 to 1% by weight of solute derived from (a) a mixture of monoand di-oxo-octyl and monoand di-n-decyl phosphates, and (b) 2-ethylhexylamine.

5. A composition of claim 1 containing 1 to 3% by weight of solute derived from (a) a mixture of monoand bis(tridecyl) phosphates, and (b) 2-ethylhexylamine.

6. A composition of claim 1 containing 1 to 3% by weight of solute derived from (a) a mixture of monoand di-oxo-octyl phosphates, and (b) 2-ethylhexylamine.

7. A composition of claim 1 containing 1 to 3% by weight of solute derived from (a) a mixture of monoand di-n-octyl and monoand di-n-decyl phosphates, and (b) Z-ethylhexylamine.

8. The method of removing water from solid surfaces which comprises treating said surface with the composition of claim 1.

9. The method of claim 8 in which the surface is treated with the composition of claim 2.

10. The method of claim 8 in which the surface is treated with the composition of claim 3.

11. The method of claim 8 in which the surface is treated with the composition of claim 4.

12. The method of preventing rusting of ferrous metal surfaces which comprises treating said surface with the composition of claim 1.

13. The method of claim 12 in which the surface is treated with the composition of claim 5.

14. The method of claim 12 in which the surface is treated with the composition of claim 6.

15. The method of claim 12 in which the surface is treated with the composition of claim 7.

References Cited UNITED STATES PATENTS 2,080,299 5/ 1937 Benning et al. 9l68 2,413,852 1/1947 Turner 25249.9 2,902,454 9/1959 Moore 252-364 3,003,247 10/ 1961 Sherliker 34-9 3,291,745 12/1966 Martens 252364 X FOREIGN PATENTS 835,072 5/1960 Great Britain.

LEON D. ROSDOL, Primary Examiner.

S. D. SCHWARTZ, Assistant Examiner.

Patent No. 3,397,150

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION August 13, 1968 James Gordon Burt et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 59, "di-oxo-octyl" should read di-n-octyl Signed and sealed this 6th day of January 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

